Spark-plug.



J. P. TRACY.

SPARK PLUG. APPLIOATION FILED 11.211,1, 1912.

1,093,744. Patented Apr. 21, 1914.

fnl/enfer JOSEPH F. TRACY, F CHICAGO, ILLINOIS.

SPARK-PLUG.

Specification of Letters Patent.

Patented Apr. 2.1, 1914.

Application filed April 1, 1912. Serial No. 687,864.

To all whom `4it may concern Be it known that I, JOSEPH F. TRACY, a citizen of the United States, and a resident of the city of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specilication.

My invention relates to improvements in spark plugs, and has for its object the provision of a spark plug provided with means whereby the operativeness or inoperativeness of said plug may be readily detected.

The invention consists in the combinations and arrangements of parts hereinafter described and claimed.

The invention will be best understood by reference to the accompanying .drawing forming a part of this specification, and which 1s a longitudinal section of a spark plug attachment embodying my invention and shown in position for use on an ordinary spark plug.

The preferred form of construction, as illustrated in the drawing, comprises an ordinary spark plug 1 threaded into the head 2 of an ordinary explosive engine cyl* inder and provided with the usual spark gap 3 within the cylinder. The usual central-conductor 4 of the spark plug is extended outwardly beyond the outer end of the spark plug and a Washer 5 of fiber or othervsuitable insulating material is placed over the outer end of the s ark plug around conductor 4 and secure in position by means of a nut 6 threaded on said conductor. A metallic shell 7 is threaded to the outer end of spark plug 1 and is provided with sight openings 8 in its sides, as shown. A leather washer 9 is arranged Within shell 7 on the outer side of Washer 5 and a glass tube or' casing 10 is arranged in shell 7 with its inner end resting upon Washer 9. Another leather washer 11 is arranged in shell 7 abutting the outer end of casing 10 and a plug 12 of fiber or other suitable insulating material is threaded in the outer end of shell 7 to secure Washer 11 and casing 10 in position therein. A nut 13 is embedded in plug 12 and a second conductor 14 is passed centrally through plug 12 and nut 13 in alinement with conductor 4 to form a supplemental spark gap 15 within casing 10. A metallic washer 16 is arranged on conductor 14 against the outer side of plug 12, and nuts 17 are arranged on the outer end of conductor 14 to serve to lock saidA conductor in adjusted positions and also as a means for attaching an electric wire to conductor 14.

In use, one of the wires of the ignition circuit is connected with the conductor 14 by means of nuts 16 and 17, the other being connected with the frame of the engine in the usual manner. This causes the current to traverse conductors 14 and 4 and jump both of the gaps 15 and 3. The spark caused at the gap 15 may be readily Seen at the openings 8, thus indicating to the operator whether the spark is properly jumping ignition gap 3. If desired, the air may be exhausted from casing 10 to reduce the friction in gap 15, since any friction in this gap is so inuch wasted energy. If desired, conductor 14 may be adjusted until it contacts with conductor 4, thus eliminating gap 15 and obviat-ing the waste of energy therein. Then, when it is desired to test to determine whether or not the 'spark is properly jumping gap 3, conduct-or 14 may be adjusted to forni the gap 15 and a spark in said gap will indicate that a suitable spark is being formed in gap 3.

While I have illustrated and described the preferred form of construction 'for' carrying my invention into eil'ect, this is capable of variation and modification without departing from the spirit of the invention. I, therefore, do not Wish to be limited to the exact details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claim.

Having described niy invention, what I claim as new and desire to secure by Letters i Patent, is:

The combination with a spark plug having a central conductor projecting outwardly and beyond said plug; a metallic shell threaded to the outer end of said plug and provided with side openings; a glass casing in said shell; a plug of insulating material threaded in the outer end o'f said shell and holding said casing iii position; a nut embedded in said insulating plug, a second conductor passin through said insulating plug and threa ed in said nut in alinement with said first mentioned con- In testimony whereof I have signed my ductor; and nuts on the outer end of said name to this specification in the presence of second conductor and coperating with said two subscribing Witnesses.

embedded nut t0 lock said conductor in ad- JOSEPH F. TRACY.

justed positions, and to rfurnish a means for Witnesses:

seeming the wire to said second conductor, JOSHUA R. H. Porrs, substantially as described. ARTHUR A. OLSON. 

